When you find a place which spellcasters are going to hold down, use the Glyph of Lesser Energy, Ward of Stability and Ward Against Melee to buff that position. In GvG, this is very useful for defending your Guild Lord or attacking theirs. In HA, it is useful for holding a position while the Ghostly Hero takes it.

In Competitive Missions, place down wards around NPC positions to protect them and bond them as necessary.